The Electrocardiographic Exercise Test in a Population with Reduced Workup Bias: Diagnostic Performance, Computerized Interpretation, and Multivariable Prediction

Abstract

Background: Empirical scores, computerized ST-segment measurements, and equations have been proposed as tools for improving the diagnostic performance of the exercise test.

Objective: To compare the diagnostic utility of these scores, measurements, and equations with that of visual ST-segment measurements in patients with reduced workup bias.

Design: Prospective analysis.

Setting: 12 university-affiliated Veterans Affairs Medical Centers.

Patients: 814 consecutive patients who presented with angina pectoris and agreed to undergo both exercise testing and coronary angiography.

Measurements: Digital electrocardiographic recorders and angiographic calipers were used for testing at each site, and test results were sent to core laboratories.

Results: Although 25% of patients had previously had testing, workup bias was reduced, as shown by comparison with a pilot study group. This reduction resulted in a sensitivity of 45% and a specificity of 85% for visual analysis. Computerized measurements and visual analysis had similar diagnostic power. Equations incorporating nonelectrocardiographic variables and either visual or computerized ST-segment measurement had similar discrimination and were superior to single ST-segment measurements. These equations correctly classified 5 more patients of every 100 tested (areas under the receiver-operating characteristic curve, 0.80 for equations and 0.68 for visual analysis; P < 0.001) in this population with a 50% prevalence of disease.

Conclusions: Standard exercise tests had lower sensitivity but higher specificity in this population with reduced work-up bias than in previous studies. Computerized ST-segment measurements were similar to visual ST-segment measurements made by cardiologists. Considering more than ST-segment measurements can enhance the diagnostic power of the exercise test.

*For members of the Veterans Affairs Cooperative Study in Health Services #016 (QUEXTA) Study Group, see Appendix 2.